src/libsyntax/ext/expand.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use ast::{self, Block, Ident, PatKind};
  12 use ast::{Name, MacStmtStyle, StmtKind, ItemKind};
  13 use attr::{self, HasAttrs};
  14 use codemap::{ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
  15 use config::{is_test_or_bench, StripUnconfigured};
  16 use ext::base::*;
  17 use ext::derive::{add_derived_markers, collect_derives};
  18 use ext::hygiene::Mark;
  19 use ext::placeholders::{placeholder, PlaceholderExpander};
  20 use feature_gate::{self, Features, is_builtin_attr};
  21 use fold;
  22 use fold::*;
  23 use parse::{filemap_to_stream, ParseSess, DirectoryOwnership, PResult, token};
  24 use parse::parser::Parser;
  25 use print::pprust;
  26 use ptr::P;
  27 use std_inject;
  28 use symbol::Symbol;
  29 use symbol::keywords;
  30 use syntax_pos::{self, Span, ExpnId};
  31 use tokenstream::TokenStream;
  32 use util::small_vector::SmallVector;
  33 use visit::Visitor;
  34
  35 use std::collections::HashMap;
  36 use std::mem;
  37 use std::path::PathBuf;
  38 use std::rc::Rc;
  39
  40 macro_rules! expansions {
  41     ($($kind:ident: $ty:ty [$($vec:ident, $ty_elt:ty)*], $kind_name:expr, .$make:ident,
  42             $(.$fold:ident)*  $(lift .$fold_elt:ident)*,
  43             $(.$visit:ident)*  $(lift .$visit_elt:ident)*;)*) => {
  44         #[derive(Copy, Clone, PartialEq, Eq)]
  45         pub enum ExpansionKind { OptExpr, $( $kind, )*  }
  46         pub enum Expansion { OptExpr(Option<P<ast::Expr>>), $( $kind($ty), )* }
  47
  48         impl ExpansionKind {
  49             pub fn name(self) -> &'static str {
  50                 match self {
  51                     ExpansionKind::OptExpr => "expression",
  52                     $( ExpansionKind::$kind => $kind_name, )*
  53                 }
  54             }
  55
  56             fn make_from<'a>(self, result: Box<MacResult + 'a>) -> Option<Expansion> {
  57                 match self {
  58                     ExpansionKind::OptExpr => result.make_expr().map(Some).map(Expansion::OptExpr),
  59                     $( ExpansionKind::$kind => result.$make().map(Expansion::$kind), )*
  60                 }
  61             }
  62         }
  63
  64         impl Expansion {
  65             pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
  66                 match self {
  67                     Expansion::OptExpr(expr) => expr,
  68                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  69                 }
  70             }
  71             $( pub fn $make(self) -> $ty {
  72                 match self {
  73                     Expansion::$kind(ast) => ast,
  74                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  75                 }
  76             } )*
  77
  78             pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
  79                 use self::Expansion::*;
  80                 match self {
  81                     OptExpr(expr) => OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
  82                     $($( $kind(ast) => $kind(folder.$fold(ast)), )*)*
  83                     $($( $kind(ast) => {
  84                         $kind(ast.into_iter().flat_map(|ast| folder.$fold_elt(ast)).collect())
  85                     }, )*)*
  86                 }
  87             }
  88
  89             pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
  90                 match *self {
  91                     Expansion::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
  92                     Expansion::OptExpr(None) => {}
  93                     $($( Expansion::$kind(ref ast) => visitor.$visit(ast), )*)*
  94                     $($( Expansion::$kind(ref ast) => for ast in &ast[..] {
  95                         visitor.$visit_elt(ast);
  96                     }, )*)*
  97                 }
  98             }
  99         }
 100
 101         impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
 102             fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 103                 self.expand(Expansion::OptExpr(Some(expr))).make_opt_expr()
 104             }
 105             $($(fn $fold(&mut self, node: $ty) -> $ty {
 106                 self.expand(Expansion::$kind(node)).$make()
 107             })*)*
 108             $($(fn $fold_elt(&mut self, node: $ty_elt) -> $ty {
 109                 self.expand(Expansion::$kind(SmallVector::one(node))).$make()
 110             })*)*
 111         }
 112
 113         impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
 114             $(fn $make(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>) -> Option<$ty> {
 115                 Some(self.make(ExpansionKind::$kind).$make())
 116             })*
 117         }
 118     }
 119 }
 120
 121 expansions! {
 122     Expr: P<ast::Expr> [], "expression", .make_expr, .fold_expr, .visit_expr;
 123     Pat: P<ast::Pat>   [], "pattern",    .make_pat,  .fold_pat,  .visit_pat;
 124     Ty: P<ast::Ty>     [], "type",       .make_ty,   .fold_ty,   .visit_ty;
 125     Stmts: SmallVector<ast::Stmt> [SmallVector, ast::Stmt],
 126         "statement",  .make_stmts,       lift .fold_stmt, lift .visit_stmt;
 127     Items: SmallVector<P<ast::Item>> [SmallVector, P<ast::Item>],
 128         "item",       .make_items,       lift .fold_item, lift .visit_item;
 129     TraitItems: SmallVector<ast::TraitItem> [SmallVector, ast::TraitItem],
 130         "trait item", .make_trait_items, lift .fold_trait_item, lift .visit_trait_item;
 131     ImplItems: SmallVector<ast::ImplItem> [SmallVector, ast::ImplItem],
 132         "impl item",  .make_impl_items,  lift .fold_impl_item,  lift .visit_impl_item;
 133 }
 134
 135 impl ExpansionKind {
 136     fn dummy(self, span: Span) -> Expansion {
 137         self.make_from(DummyResult::any(span)).unwrap()
 138     }
 139
 140     fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I) -> Expansion {
 141         let items = items.into_iter();
 142         match self {
 143             ExpansionKind::Items =>
 144                 Expansion::Items(items.map(Annotatable::expect_item).collect()),
 145             ExpansionKind::ImplItems =>
 146                 Expansion::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
 147             ExpansionKind::TraitItems =>
 148                 Expansion::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
 149             _ => unreachable!(),
 150         }
 151     }
 152 }
 153
 154 pub struct Invocation {
 155     pub kind: InvocationKind,
 156     expansion_kind: ExpansionKind,
 157     pub expansion_data: ExpansionData,
 158 }
 159
 160 pub enum InvocationKind {
 161     Bang {
 162         mac: ast::Mac,
 163         ident: Option<Ident>,
 164         span: Span,
 165     },
 166     Attr {
 167         attr: Option<ast::Attribute>,
 168         traits: Vec<(Symbol, Span)>,
 169         item: Annotatable,
 170     },
 171     Derive {
 172         name: Symbol,
 173         span: Span,
 174         item: Annotatable,
 175     },
 176 }
 177
 178 impl Invocation {
 179     fn span(&self) -> Span {
 180         match self.kind {
 181             InvocationKind::Bang { span, .. } => span,
 182             InvocationKind::Attr { attr: Some(ref attr), .. } => attr.span,
 183             InvocationKind::Attr { attr: None, .. } => syntax_pos::DUMMY_SP,
 184             InvocationKind::Derive { span, .. } => span,
 185         }
 186     }
 187 }
 188
 189 pub struct MacroExpander<'a, 'b:'a> {
 190     pub cx: &'a mut ExtCtxt<'b>,
 191     monotonic: bool, // c.f. `cx.monotonic_expander()`
 192 }
 193
 194 impl<'a, 'b> MacroExpander<'a, 'b> {
 195     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
 196         MacroExpander { cx: cx, monotonic: monotonic }
 197     }
 198
 199     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 200         self.cx.crate_root = std_inject::injected_crate_name(&krate);
 201         let mut module = ModuleData {
 202             mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
 203             directory: PathBuf::from(self.cx.codemap().span_to_filename(krate.span)),
 204         };
 205         module.directory.pop();
 206         self.cx.current_expansion.module = Rc::new(module);
 207
 208         let krate_item = Expansion::Items(SmallVector::one(P(ast::Item {
 209             attrs: krate.attrs,
 210             span: krate.span,
 211             node: ast::ItemKind::Mod(krate.module),
 212             ident: keywords::Invalid.ident(),
 213             id: ast::DUMMY_NODE_ID,
 214             vis: ast::Visibility::Public,
 215         })));
 216
 217         match self.expand(krate_item).make_items().pop().unwrap().unwrap() {
 218             ast::Item { attrs, node: ast::ItemKind::Mod(module), .. } => {
 219                 krate.attrs = attrs;
 220                 krate.module = module;
 221             },
 222             _ => unreachable!(),
 223         };
 224
 225         krate
 226     }
 227
 228     // Fully expand all the invocations in `expansion`.
 229     fn expand(&mut self, expansion: Expansion) -> Expansion {
 230         let orig_expansion_data = self.cx.current_expansion.clone();
 231         self.cx.current_expansion.depth = 0;
 232
 233         let (expansion, mut invocations) = self.collect_invocations(expansion, &[]);
 234         self.resolve_imports();
 235         invocations.reverse();
 236
 237         let mut expansions = Vec::new();
 238         let mut derives = HashMap::new();
 239         let mut undetermined_invocations = Vec::new();
 240         let (mut progress, mut force) = (false, !self.monotonic);
 241         loop {
 242             let mut invoc = if let Some(invoc) = invocations.pop() {
 243                 invoc
 244             } else {
 245                 self.resolve_imports();
 246                 if undetermined_invocations.is_empty() { break }
 247                 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
 248                 force = !mem::replace(&mut progress, false);
 249                 continue
 250             };
 251
 252             let scope =
 253                 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
 254             let ext = match self.cx.resolver.resolve_invoc(&mut invoc, scope, force) {
 255                 Ok(ext) => Some(ext),
 256                 Err(Determinacy::Determined) => None,
 257                 Err(Determinacy::Undetermined) => {
 258                     undetermined_invocations.push(invoc);
 259                     continue
 260                 }
 261             };
 262
 263             progress = true;
 264             let ExpansionData { depth, mark, .. } = invoc.expansion_data;
 265             self.cx.current_expansion = invoc.expansion_data.clone();
 266
 267             self.cx.current_expansion.mark = scope;
 268             // FIXME(jseyfried): Refactor out the following logic
 269             let (expansion, new_invocations) = if let Some(ext) = ext {
 270                 if let Some(ext) = ext {
 271                     let expansion = self.expand_invoc(invoc, ext);
 272                     self.collect_invocations(expansion, &[])
 273                 } else if let InvocationKind::Attr { attr: None, traits, item } = invoc.kind {
 274                     let item = item
 275                         .map_attrs(|mut attrs| { attrs.retain(|a| a.name() != "derive"); attrs });
 276                     let item_with_markers =
 277                         add_derived_markers(&mut self.cx, &traits, item.clone());
 278                     let derives = derives.entry(invoc.expansion_data.mark).or_insert_with(Vec::new);
 279
 280                     for &(name, span) in &traits {
 281                         let mark = Mark::fresh();
 282                         derives.push(mark);
 283                         let path = ast::Path::from_ident(span, Ident::with_empty_ctxt(name));
 284                         let item = match self.cx.resolver.resolve_macro(
 285                                 Mark::root(), &path, MacroKind::Derive, false) {
 286                             Ok(ext) => match *ext {
 287                                 SyntaxExtension::BuiltinDerive(..) => item_with_markers.clone(),
 288                                 _ => item.clone(),
 289                             },
 290                             _ => item.clone(),
 291                         };
 292                         invocations.push(Invocation {
 293                             kind: InvocationKind::Derive { name: name, span: span, item: item },
 294                             expansion_kind: invoc.expansion_kind,
 295                             expansion_data: ExpansionData {
 296                                 mark: mark,
 297                                 ..invoc.expansion_data.clone()
 298                             },
 299                         });
 300                     }
 301                     let expansion = invoc.expansion_kind
 302                         .expect_from_annotatables(::std::iter::once(item_with_markers));
 303                     self.collect_invocations(expansion, derives)
 304                 } else {
 305                     unreachable!()
 306                 }
 307             } else {
 308                 self.collect_invocations(invoc.expansion_kind.dummy(invoc.span()), &[])
 309             };
 310
 311             if expansions.len() < depth {
 312                 expansions.push(Vec::new());
 313             }
 314             expansions[depth - 1].push((mark, expansion));
 315             if !self.cx.ecfg.single_step {
 316                 invocations.extend(new_invocations.into_iter().rev());
 317             }
 318         }
 319
 320         self.cx.current_expansion = orig_expansion_data;
 321
 322         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 323         while let Some(expansions) = expansions.pop() {
 324             for (mark, expansion) in expansions.into_iter().rev() {
 325                 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
 326                 placeholder_expander.add(mark.as_placeholder_id(), expansion, derives);
 327             }
 328         }
 329
 330         expansion.fold_with(&mut placeholder_expander)
 331     }
 332
 333     fn resolve_imports(&mut self) {
 334         if self.monotonic {
 335             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 336             self.cx.resolver.resolve_imports();
 337             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 338         }
 339     }
 340
 341     fn collect_invocations(&mut self, expansion: Expansion, derives: &[Mark])
 342                            -> (Expansion, Vec<Invocation>) {
 343         let result = {
 344             let mut collector = InvocationCollector {
 345                 cfg: StripUnconfigured {
 346                     should_test: self.cx.ecfg.should_test,
 347                     sess: self.cx.parse_sess,
 348                     features: self.cx.ecfg.features,
 349                 },
 350                 cx: self.cx,
 351                 invocations: Vec::new(),
 352                 monotonic: self.monotonic,
 353             };
 354             (expansion.fold_with(&mut collector), collector.invocations)
 355         };
 356
 357         if self.monotonic {
 358             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 359             let mark = self.cx.current_expansion.mark;
 360             self.cx.resolver.visit_expansion(mark, &result.0, derives);
 361             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 362         }
 363
 364         result
 365     }
 366
 367     fn expand_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 368         match invoc.kind {
 369             InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext),
 370             InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext),
 371             InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext),
 372         }
 373     }
 374
 375     fn expand_attr_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 376         let Invocation { expansion_kind: kind, .. } = invoc;
 377         let (attr, item) = match invoc.kind {
 378             InvocationKind::Attr { attr, item, .. } => (attr.unwrap(), item),
 379             _ => unreachable!(),
 380         };
 381
 382         attr::mark_used(&attr);
 383         let name = attr.name();
 384         self.cx.bt_push(ExpnInfo {
 385             call_site: attr.span,
 386             callee: NameAndSpan {
 387                 format: MacroAttribute(name),
 388                 span: Some(attr.span),
 389                 allow_internal_unstable: false,
 390             }
 391         });
 392
 393         match *ext {
 394             MultiModifier(ref mac) => {
 395                 let item = mac.expand(self.cx, attr.span, &attr.value, item);
 396                 kind.expect_from_annotatables(item)
 397             }
 398             MultiDecorator(ref mac) => {
 399                 let mut items = Vec::new();
 400                 mac.expand(self.cx, attr.span, &attr.value, &item,
 401                            &mut |item| items.push(item));
 402                 items.push(item);
 403                 kind.expect_from_annotatables(items)
 404             }
 405             SyntaxExtension::AttrProcMacro(ref mac) => {
 406                 let attr_toks = stream_for_attr_args(&attr, &self.cx.parse_sess);
 407                 let item_toks = stream_for_item(&item, &self.cx.parse_sess);
 408
 409                 let span = Span {
 410                     expn_id: self.cx.codemap().record_expansion(ExpnInfo {
 411                         call_site: attr.span,
 412                         callee: NameAndSpan {
 413                             format: MacroAttribute(name),
 414                             span: None,
 415                             allow_internal_unstable: false,
 416                         },
 417                     }),
 418                     ..attr.span
 419                 };
 420
 421                 let tok_result = mac.expand(self.cx, attr.span, attr_toks, item_toks);
 422                 self.parse_expansion(tok_result, kind, name, span)
 423             }
 424             SyntaxExtension::ProcMacroDerive(..) | SyntaxExtension::BuiltinDerive(..) => {
 425                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", name));
 426                 kind.dummy(attr.span)
 427             }
 428             _ => {
 429                 let msg = &format!("macro `{}` may not be used in attributes", name);
 430                 self.cx.span_err(attr.span, &msg);
 431                 kind.dummy(attr.span)
 432             }
 433         }
 434     }
 435
 436     /// Expand a macro invocation. Returns the result of expansion.
 437     fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 438         let (mark, kind) = (invoc.expansion_data.mark, invoc.expansion_kind);
 439         let (mac, ident, span) = match invoc.kind {
 440             InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
 441             _ => unreachable!(),
 442         };
 443         let path = &mac.node.path;
 444
 445         let extname = path.segments.last().unwrap().identifier.name;
 446         let ident = ident.unwrap_or(keywords::Invalid.ident());
 447         let marked_tts =
 448             noop_fold_tts(mac.node.stream(), &mut Marker { mark: mark, expn_id: None });
 449         let opt_expanded = match *ext {
 450             NormalTT(ref expandfun, exp_span, allow_internal_unstable) => {
 451                 if ident.name != keywords::Invalid.name() {
 452                     let msg =
 453                         format!("macro {}! expects no ident argument, given '{}'", extname, ident);
 454                     self.cx.span_err(path.span, &msg);
 455                     return kind.dummy(span);
 456                 }
 457
 458                 self.cx.bt_push(ExpnInfo {
 459                     call_site: span,
 460                     callee: NameAndSpan {
 461                         format: MacroBang(extname),
 462                         span: exp_span,
 463                         allow_internal_unstable: allow_internal_unstable,
 464                     },
 465                 });
 466
 467                 kind.make_from(expandfun.expand(self.cx, span, marked_tts))
 468             }
 469
 470             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 471                 if ident.name == keywords::Invalid.name() {
 472                     self.cx.span_err(path.span,
 473                                     &format!("macro {}! expects an ident argument", extname));
 474                     return kind.dummy(span);
 475                 };
 476
 477                 self.cx.bt_push(ExpnInfo {
 478                     call_site: span,
 479                     callee: NameAndSpan {
 480                         format: MacroBang(extname),
 481                         span: tt_span,
 482                         allow_internal_unstable: allow_internal_unstable,
 483                     }
 484                 });
 485
 486                 let input: Vec<_> = marked_tts.into_trees().collect();
 487                 kind.make_from(expander.expand(self.cx, span, ident, input))
 488             }
 489
 490             MultiDecorator(..) | MultiModifier(..) | SyntaxExtension::AttrProcMacro(..) => {
 491                 self.cx.span_err(path.span,
 492                                  &format!("`{}` can only be used in attributes", extname));
 493                 return kind.dummy(span);
 494             }
 495
 496             SyntaxExtension::ProcMacroDerive(..) | SyntaxExtension::BuiltinDerive(..) => {
 497                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", extname));
 498                 return kind.dummy(span);
 499             }
 500
 501             SyntaxExtension::ProcMacro(ref expandfun) => {
 502                 if ident.name != keywords::Invalid.name() {
 503                     let msg =
 504                         format!("macro {}! expects no ident argument, given '{}'", extname, ident);
 505                     self.cx.span_err(path.span, &msg);
 506                     return kind.dummy(span);
 507                 }
 508
 509                 self.cx.bt_push(ExpnInfo {
 510                     call_site: span,
 511                     callee: NameAndSpan {
 512                         format: MacroBang(extname),
 513                         // FIXME procedural macros do not have proper span info
 514                         // yet, when they do, we should use it here.
 515                         span: None,
 516                         // FIXME probably want to follow macro_rules macros here.
 517                         allow_internal_unstable: false,
 518                     },
 519                 });
 520
 521                 let tok_result = expandfun.expand(self.cx, span, marked_tts);
 522                 Some(self.parse_expansion(tok_result, kind, extname, span))
 523             }
 524         };
 525
 526         let expanded = if let Some(expanded) = opt_expanded {
 527             expanded
 528         } else {
 529             let msg = format!("non-{kind} macro in {kind} position: {name}",
 530                               name = path.segments[0].identifier.name, kind = kind.name());
 531             self.cx.span_err(path.span, &msg);
 532             return kind.dummy(span);
 533         };
 534
 535         expanded.fold_with(&mut Marker {
 536             mark: mark,
 537             expn_id: Some(self.cx.backtrace()),
 538         })
 539     }
 540
 541     /// Expand a derive invocation. Returns the result of expansion.
 542     fn expand_derive_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 543         let Invocation { expansion_kind: kind, .. } = invoc;
 544         let (name, span, item) = match invoc.kind {
 545             InvocationKind::Derive { name, span, item } => (name, span, item),
 546             _ => unreachable!(),
 547         };
 548
 549         let mitem = ast::MetaItem { name: name, span: span, node: ast::MetaItemKind::Word };
 550         let pretty_name = Symbol::intern(&format!("derive({})", name));
 551
 552         self.cx.bt_push(ExpnInfo {
 553             call_site: span,
 554             callee: NameAndSpan {
 555                 format: MacroAttribute(pretty_name),
 556                 span: Some(span),
 557                 allow_internal_unstable: false,
 558             }
 559         });
 560
 561         match *ext {
 562             SyntaxExtension::ProcMacroDerive(ref ext, _) => {
 563                 let span = Span {
 564                     expn_id: self.cx.codemap().record_expansion(ExpnInfo {
 565                         call_site: span,
 566                         callee: NameAndSpan {
 567                             format: MacroAttribute(pretty_name),
 568                             span: None,
 569                             allow_internal_unstable: false,
 570                         },
 571                     }),
 572                     ..span
 573                 };
 574                 return kind.expect_from_annotatables(ext.expand(self.cx, span, &mitem, item));
 575             }
 576             SyntaxExtension::BuiltinDerive(func) => {
 577                 let span = Span {
 578                     expn_id: self.cx.codemap().record_expansion(ExpnInfo {
 579                         call_site: span,
 580                         callee: NameAndSpan {
 581                             format: MacroAttribute(pretty_name),
 582                             span: None,
 583                             allow_internal_unstable: true,
 584                         },
 585                     }),
 586                     ..span
 587                 };
 588                 let mut items = Vec::new();
 589                 func(self.cx, span, &mitem, &item, &mut |a| {
 590                     items.push(a)
 591                 });
 592                 return kind.expect_from_annotatables(items);
 593             }
 594             _ => {
 595                 let msg = &format!("macro `{}` may not be used for derive attributes", name);
 596                 self.cx.span_err(span, &msg);
 597                 kind.dummy(span)
 598             }
 599         }
 600     }
 601
 602     fn parse_expansion(&mut self, toks: TokenStream, kind: ExpansionKind, name: Name, span: Span)
 603                        -> Expansion {
 604         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 605         let expansion = match parser.parse_expansion(kind, false) {
 606             Ok(expansion) => expansion,
 607             Err(mut err) => {
 608                 err.emit();
 609                 return kind.dummy(span);
 610             }
 611         };
 612         parser.ensure_complete_parse(name, kind.name(), span);
 613         // FIXME better span info
 614         expansion.fold_with(&mut ChangeSpan { span: span })
 615     }
 616 }
 617
 618 impl<'a> Parser<'a> {
 619     pub fn parse_expansion(&mut self, kind: ExpansionKind, macro_legacy_warnings: bool)
 620                            -> PResult<'a, Expansion> {
 621         Ok(match kind {
 622             ExpansionKind::Items => {
 623                 let mut items = SmallVector::new();
 624                 while let Some(item) = self.parse_item()? {
 625                     items.push(item);
 626                 }
 627                 Expansion::Items(items)
 628             }
 629             ExpansionKind::TraitItems => {
 630                 let mut items = SmallVector::new();
 631                 while self.token != token::Eof {
 632                     items.push(self.parse_trait_item()?);
 633                 }
 634                 Expansion::TraitItems(items)
 635             }
 636             ExpansionKind::ImplItems => {
 637                 let mut items = SmallVector::new();
 638                 while self.token != token::Eof {
 639                     items.push(self.parse_impl_item()?);
 640                 }
 641                 Expansion::ImplItems(items)
 642             }
 643             ExpansionKind::Stmts => {
 644                 let mut stmts = SmallVector::new();
 645                 while self.token != token::Eof &&
 646                       // won't make progress on a `}`
 647                       self.token != token::CloseDelim(token::Brace) {
 648                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
 649                         stmts.push(stmt);
 650                     }
 651                 }
 652                 Expansion::Stmts(stmts)
 653             }
 654             ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
 655             ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
 656             ExpansionKind::Ty => Expansion::Ty(self.parse_ty_no_plus()?),
 657             ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
 658         })
 659     }
 660
 661     pub fn ensure_complete_parse(&mut self, macro_name: ast::Name, kind_name: &str, span: Span) {
 662         if self.token != token::Eof {
 663             let msg = format!("macro expansion ignores token `{}` and any following",
 664                               self.this_token_to_string());
 665             let mut err = self.diagnostic().struct_span_err(self.span, &msg);
 666             let msg = format!("caused by the macro expansion here; the usage \
 667                                of `{}!` is likely invalid in {} context",
 668                                macro_name, kind_name);
 669             err.span_note(span, &msg).emit();
 670         }
 671     }
 672 }
 673
 674 struct InvocationCollector<'a, 'b: 'a> {
 675     cx: &'a mut ExtCtxt<'b>,
 676     cfg: StripUnconfigured<'a>,
 677     invocations: Vec<Invocation>,
 678     monotonic: bool,
 679 }
 680
 681 macro_rules! fully_configure {
 682     ($this:ident, $node:ident, $noop_fold:ident) => {
 683         match $noop_fold($node, &mut $this.cfg).pop() {
 684             Some(node) => node,
 685             None => return SmallVector::new(),
 686         }
 687     }
 688 }
 689
 690 impl<'a, 'b> InvocationCollector<'a, 'b> {
 691     fn collect(&mut self, expansion_kind: ExpansionKind, kind: InvocationKind) -> Expansion {
 692         let mark = Mark::fresh();
 693         self.invocations.push(Invocation {
 694             kind: kind,
 695             expansion_kind: expansion_kind,
 696             expansion_data: ExpansionData {
 697                 mark: mark,
 698                 depth: self.cx.current_expansion.depth + 1,
 699                 ..self.cx.current_expansion.clone()
 700             },
 701         });
 702         placeholder(expansion_kind, mark.as_placeholder_id())
 703     }
 704
 705     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: ExpansionKind) -> Expansion {
 706         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
 707     }
 708
 709     fn collect_attr(&mut self,
 710                     attr: Option<ast::Attribute>,
 711                     traits: Vec<(Symbol, Span)>,
 712                     item: Annotatable,
 713                     kind: ExpansionKind)
 714                     -> Expansion {
 715         if !traits.is_empty() &&
 716            (kind == ExpansionKind::TraitItems || kind == ExpansionKind::ImplItems) {
 717             self.cx.span_err(traits[0].1, "`derive` can be only be applied to items");
 718             return kind.expect_from_annotatables(::std::iter::once(item));
 719         }
 720         self.collect(kind, InvocationKind::Attr { attr: attr, traits: traits, item: item })
 721     }
 722
 723     // If `item` is an attr invocation, remove and return the macro attribute.
 724     fn classify_item<T>(&mut self, mut item: T) -> (Option<ast::Attribute>, Vec<(Symbol, Span)>, T)
 725         where T: HasAttrs,
 726     {
 727         let (mut attr, mut traits) = (None, Vec::new());
 728
 729         item = item.map_attrs(|mut attrs| {
 730             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs) {
 731                 attr = Some(legacy_attr_invoc);
 732                 return attrs;
 733             }
 734
 735             if self.cx.ecfg.proc_macro_enabled() {
 736                 attr = find_attr_invoc(&mut attrs);
 737             }
 738             traits = collect_derives(&mut self.cx, &mut attrs);
 739             attrs
 740         });
 741
 742         (attr, traits, item)
 743     }
 744
 745     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
 746         self.cfg.configure(node)
 747     }
 748
 749     // Detect use of feature-gated or invalid attributes on macro invocations
 750     // since they will not be detected after macro expansion.
 751     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
 752         let codemap = &self.cx.parse_sess.codemap();
 753         let features = self.cx.ecfg.features.unwrap();
 754         for attr in attrs.iter() {
 755             feature_gate::check_attribute(&attr, &self.cx.parse_sess, codemap, features);
 756         }
 757     }
 758 }
 759
 760 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
 761     for i in 0 .. attrs.len() {
 762         if !attr::is_known(&attrs[i]) && !is_builtin_attr(&attrs[i]) {
 763              return Some(attrs.remove(i));
 764         }
 765     }
 766
 767     None
 768 }
 769
 770 // These are pretty nasty. Ideally, we would keep the tokens around, linked from
 771 // the AST. However, we don't so we need to create new ones. Since the item might
 772 // have come from a macro expansion (possibly only in part), we can't use the
 773 // existing codemap.
 774 //
 775 // Therefore, we must use the pretty printer (yuck) to turn the AST node into a
 776 // string, which we then re-tokenise (double yuck), but first we have to patch
 777 // the pretty-printed string on to the end of the existing codemap (infinity-yuck).
 778 fn stream_for_item(item: &Annotatable, parse_sess: &ParseSess) -> TokenStream {
 779     let text = match *item {
 780         Annotatable::Item(ref i) => pprust::item_to_string(i),
 781         Annotatable::TraitItem(ref ti) => pprust::trait_item_to_string(ti),
 782         Annotatable::ImplItem(ref ii) => pprust::impl_item_to_string(ii),
 783     };
 784     string_to_stream(text, parse_sess)
 785 }
 786
 787 fn stream_for_attr_args(attr: &ast::Attribute, parse_sess: &ParseSess) -> TokenStream {
 788     use ast::MetaItemKind::*;
 789     use print::pp::Breaks;
 790     use print::pprust::PrintState;
 791
 792     let token_string = match attr.value.node {
 793         // For `#[foo]`, an empty token
 794         Word => return TokenStream::empty(),
 795         // For `#[foo(bar, baz)]`, returns `(bar, baz)`
 796         List(ref items) => pprust::to_string(|s| {
 797             s.popen()?;
 798             s.commasep(Breaks::Consistent,
 799                        &items[..],
 800                        |s, i| s.print_meta_list_item(&i))?;
 801             s.pclose()
 802         }),
 803         // For `#[foo = "bar"]`, returns `= "bar"`
 804         NameValue(ref lit) => pprust::to_string(|s| {
 805             s.word_space("=")?;
 806             s.print_literal(lit)
 807         }),
 808     };
 809
 810     string_to_stream(token_string, parse_sess)
 811 }
 812
 813 fn string_to_stream(text: String, parse_sess: &ParseSess) -> TokenStream {
 814     let filename = String::from("<macro expansion>");
 815     filemap_to_stream(parse_sess, parse_sess.codemap().new_filemap(filename, None, text))
 816 }
 817
 818 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 819     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 820         let mut expr = self.cfg.configure_expr(expr).unwrap();
 821         expr.node = self.cfg.configure_expr_kind(expr.node);
 822
 823         if let ast::ExprKind::Mac(mac) = expr.node {
 824             self.check_attributes(&expr.attrs);
 825             self.collect_bang(mac, expr.span, ExpansionKind::Expr).make_expr()
 826         } else {
 827             P(noop_fold_expr(expr, self))
 828         }
 829     }
 830
 831     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 832         let mut expr = configure!(self, expr).unwrap();
 833         expr.node = self.cfg.configure_expr_kind(expr.node);
 834
 835         if let ast::ExprKind::Mac(mac) = expr.node {
 836             self.check_attributes(&expr.attrs);
 837             self.collect_bang(mac, expr.span, ExpansionKind::OptExpr).make_opt_expr()
 838         } else {
 839             Some(P(noop_fold_expr(expr, self)))
 840         }
 841     }
 842
 843     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 844         let pat = self.cfg.configure_pat(pat);
 845         match pat.node {
 846             PatKind::Mac(_) => {}
 847             _ => return noop_fold_pat(pat, self),
 848         }
 849
 850         pat.and_then(|pat| match pat.node {
 851             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, ExpansionKind::Pat).make_pat(),
 852             _ => unreachable!(),
 853         })
 854     }
 855
 856     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
 857         let stmt = match self.cfg.configure_stmt(stmt) {
 858             Some(stmt) => stmt,
 859             None => return SmallVector::new(),
 860         };
 861
 862         let (mac, style, attrs) = if let StmtKind::Mac(mac) = stmt.node {
 863             mac.unwrap()
 864         } else {
 865             // The placeholder expander gives ids to statements, so we avoid folding the id here.
 866             let ast::Stmt { id, node, span } = stmt;
 867             return noop_fold_stmt_kind(node, self).into_iter().map(|node| {
 868                 ast::Stmt { id: id, node: node, span: span }
 869             }).collect()
 870         };
 871
 872         self.check_attributes(&attrs);
 873         let mut placeholder = self.collect_bang(mac, stmt.span, ExpansionKind::Stmts).make_stmts();
 874
 875         // If this is a macro invocation with a semicolon, then apply that
 876         // semicolon to the final statement produced by expansion.
 877         if style == MacStmtStyle::Semicolon {
 878             if let Some(stmt) = placeholder.pop() {
 879                 placeholder.push(stmt.add_trailing_semicolon());
 880             }
 881         }
 882
 883         placeholder
 884     }
 885
 886     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
 887         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
 888         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
 889         let result = noop_fold_block(block, self);
 890         self.cx.current_expansion.directory_ownership = old_directory_ownership;
 891         result
 892     }
 893
 894     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 895         let item = configure!(self, item);
 896
 897         let (attr, traits, mut item) = self.classify_item(item);
 898         if attr.is_some() || !traits.is_empty() {
 899             let item = Annotatable::Item(fully_configure!(self, item, noop_fold_item));
 900             return self.collect_attr(attr, traits, item, ExpansionKind::Items).make_items();
 901         }
 902
 903         match item.node {
 904             ast::ItemKind::Mac(..) => {
 905                 self.check_attributes(&item.attrs);
 906                 item.and_then(|item| match item.node {
 907                     ItemKind::Mac(mac) => {
 908                         self.collect(ExpansionKind::Items, InvocationKind::Bang {
 909                             mac: mac,
 910                             ident: Some(item.ident),
 911                             span: item.span,
 912                         }).make_items()
 913                     }
 914                     _ => unreachable!(),
 915                 })
 916             }
 917             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
 918                 if item.ident == keywords::Invalid.ident() {
 919                     return noop_fold_item(item, self);
 920                 }
 921
 922                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
 923                 let mut module = (*self.cx.current_expansion.module).clone();
 924                 module.mod_path.push(item.ident);
 925
 926                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
 927                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
 928                 // Thus, if `inner` is the dummy span, we know the module is inline.
 929                 let inline_module = item.span.contains(inner) || inner == syntax_pos::DUMMY_SP;
 930
 931                 if inline_module {
 932                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
 933                         self.cx.current_expansion.directory_ownership = DirectoryOwnership::Owned;
 934                         module.directory.push(&*path.as_str());
 935                     } else {
 936                         module.directory.push(&*item.ident.name.as_str());
 937                     }
 938                 } else {
 939                     let mut path =
 940                         PathBuf::from(self.cx.parse_sess.codemap().span_to_filename(inner));
 941                     let directory_ownership = match path.file_name().unwrap().to_str() {
 942                         Some("mod.rs") => DirectoryOwnership::Owned,
 943                         _ => DirectoryOwnership::UnownedViaMod(false),
 944                     };
 945                     path.pop();
 946                     module.directory = path;
 947                     self.cx.current_expansion.directory_ownership = directory_ownership;
 948                 }
 949
 950                 let orig_module =
 951                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
 952                 let result = noop_fold_item(item, self);
 953                 self.cx.current_expansion.module = orig_module;
 954                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
 955                 return result;
 956             }
 957             // Ensure that test functions are accessible from the test harness.
 958             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
 959                 if item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
 960                     item = item.map(|mut item| { item.vis = ast::Visibility::Public; item });
 961                 }
 962                 noop_fold_item(item, self)
 963             }
 964             _ => noop_fold_item(item, self),
 965         }
 966     }
 967
 968     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
 969         let item = configure!(self, item);
 970
 971         let (attr, traits, item) = self.classify_item(item);
 972         if attr.is_some() || !traits.is_empty() {
 973             let item =
 974                 Annotatable::TraitItem(P(fully_configure!(self, item, noop_fold_trait_item)));
 975             return self.collect_attr(attr, traits, item, ExpansionKind::TraitItems)
 976                 .make_trait_items()
 977         }
 978
 979         match item.node {
 980             ast::TraitItemKind::Macro(mac) => {
 981                 let ast::TraitItem { attrs, span, .. } = item;
 982                 self.check_attributes(&attrs);
 983                 self.collect_bang(mac, span, ExpansionKind::TraitItems).make_trait_items()
 984             }
 985             _ => fold::noop_fold_trait_item(item, self),
 986         }
 987     }
 988
 989     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
 990         let item = configure!(self, item);
 991
 992         let (attr, traits, item) = self.classify_item(item);
 993         if attr.is_some() || !traits.is_empty() {
 994             let item = Annotatable::ImplItem(P(fully_configure!(self, item, noop_fold_impl_item)));
 995             return self.collect_attr(attr, traits, item, ExpansionKind::ImplItems)
 996                 .make_impl_items();
 997         }
 998
 999         match item.node {
1000             ast::ImplItemKind::Macro(mac) => {
1001                 let ast::ImplItem { attrs, span, .. } = item;
1002                 self.check_attributes(&attrs);
1003                 self.collect_bang(mac, span, ExpansionKind::ImplItems).make_impl_items()
1004             }
1005             _ => fold::noop_fold_impl_item(item, self),
1006         }
1007     }
1008
1009     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
1010         let ty = match ty.node {
1011             ast::TyKind::Mac(_) => ty.unwrap(),
1012             _ => return fold::noop_fold_ty(ty, self),
1013         };
1014
1015         match ty.node {
1016             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, ExpansionKind::Ty).make_ty(),
1017             _ => unreachable!(),
1018         }
1019     }
1020
1021     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1022         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1023     }
1024
1025     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1026         match item {
1027             ast::ItemKind::MacroDef(..) => item,
1028             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1029         }
1030     }
1031
1032     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1033         if self.monotonic {
1034             assert_eq!(id, ast::DUMMY_NODE_ID);
1035             self.cx.resolver.next_node_id()
1036         } else {
1037             id
1038         }
1039     }
1040 }
1041
1042 pub struct ExpansionConfig<'feat> {
1043     pub crate_name: String,
1044     pub features: Option<&'feat Features>,
1045     pub recursion_limit: usize,
1046     pub trace_mac: bool,
1047     pub should_test: bool, // If false, strip `#[test]` nodes
1048     pub single_step: bool,
1049     pub keep_macs: bool,
1050 }
1051
1052 macro_rules! feature_tests {
1053     ($( fn $getter:ident = $field:ident, )*) => {
1054         $(
1055             pub fn $getter(&self) -> bool {
1056                 match self.features {
1057                     Some(&Features { $field: true, .. }) => true,
1058                     _ => false,
1059                 }
1060             }
1061         )*
1062     }
1063 }
1064
1065 impl<'feat> ExpansionConfig<'feat> {
1066     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1067         ExpansionConfig {
1068             crate_name: crate_name,
1069             features: None,
1070             recursion_limit: 64,
1071             trace_mac: false,
1072             should_test: false,
1073             single_step: false,
1074             keep_macs: false,
1075         }
1076     }
1077
1078     feature_tests! {
1079         fn enable_quotes = quote,
1080         fn enable_asm = asm,
1081         fn enable_log_syntax = log_syntax,
1082         fn enable_concat_idents = concat_idents,
1083         fn enable_trace_macros = trace_macros,
1084         fn enable_allow_internal_unstable = allow_internal_unstable,
1085         fn enable_custom_derive = custom_derive,
1086         fn proc_macro_enabled = proc_macro,
1087     }
1088 }
1089
1090 // A Marker adds the given mark to the syntax context and
1091 // sets spans' `expn_id` to the given expn_id (unless it is `None`).
1092 struct Marker { mark: Mark, expn_id: Option<ExpnId> }
1093
1094 impl Folder for Marker {
1095     fn fold_ident(&mut self, mut ident: Ident) -> Ident {
1096         ident.ctxt = ident.ctxt.apply_mark(self.mark);
1097         ident
1098     }
1099     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1100         noop_fold_mac(mac, self)
1101     }
1102
1103     fn new_span(&mut self, mut span: Span) -> Span {
1104         if let Some(expn_id) = self.expn_id {
1105             span.expn_id = expn_id;
1106         }
1107         span
1108     }
1109 }